/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/


using ASC.Xmpp.Server.Utils;
using System;
using System.Collections.Generic;

namespace ASC.Xmpp.Server.Authorization
{
	public class AuthManager
	{
		private readonly Dictionary<string, AuthToken> tokenInfos = new Dictionary<string, AuthToken>();

		private const int tokenValidity = 30; //30 min

		public string GetUserToken(string username)
		{
			if (string.IsNullOrEmpty(username)) throw new ArgumentNullException("username");

			var token = new AuthToken(username);
            lock (tokenInfos)
            {
                if (!tokenInfos.ContainsKey(token.Token))
                {
                    tokenInfos.Add(token.Token, token);
                    return token.Token;
                }
            }
			return string.Empty;
		}

		public string RestoreUserToken(string token)
		{
			if (string.IsNullOrEmpty(token)) throw new ArgumentNullException("token");
            lock (tokenInfos)
            {
                if (tokenInfos.ContainsKey(token) && (DateTime.UtcNow - tokenInfos[token].Created).TotalMinutes < tokenValidity)
                {
                    var user = tokenInfos[token].Username;
                    CleanTokens(token);
                    return user;
                }
            }
			return null;
		}

		private void CleanTokens(string tokeset)
		{
			tokenInfos.Remove(tokeset);
			foreach (var info in new Dictionary<string, AuthToken>(tokenInfos))
			{
				if ((DateTime.UtcNow - info.Value.Created).TotalMinutes > tokenValidity)
				{
					tokenInfos.Remove(info.Key); //remove token
				}
			}
		}


		private class AuthToken
		{
			public string Username
			{
				get;
				private set;
			}

			public DateTime Created
			{
				get;
				private set;
			}

			public string Token
			{
				get;
				private set;
			}

			public AuthToken(string username)
			{
				Username = username;
				Created = DateTime.UtcNow;
				Token = UniqueId.CreateNewId(50);
			}
		}
	}
}